The present invention relates to a dental elastomeric impression material of high, or respectively very high, consistency, whose consistency test disk according to ISO 4823 has a maximum diameter of 35 mm.
The consistency test according to the ISO standard is a measurement using two glass plates, wherein 0.5 ml of the elastomer to be tested is applied on the base disc and subsequently, using a second plate, is pressed under the influence of a prescribed force. The consistency is classified into different types based on the average diameter of the resulting disc.
The present invention relates to preferred materials of the type class 0, that is high viscosity or kneadable materials, also called putty mass or putties.
During dental impressions, the impression material is introduced into the oral cavity in a plastic state, where it undergoes a phase change and transitions into a firm elastic or rigid state, so that it is possible to remove the mold from the oral cavity in a fixed form and without changes to the form thereof.
Thus, the present invention relates to dental putty based on addition curing silicone. This substance class which deals with cold curing two-component systems, in which two pastes are mixed together that cure with each other after a few minutes at room temperature, is characterized by an extremely low shrinkage during the curing, and generally reproduces the situation to be modeled in the patient in a dimensionally accurate and exactly detailed manner.
Dental putty masses based on addition curing silicone are frequently used in a so-called correction impression. For this purpose, a first impression (pre-impression) of the heavy flowing or kneadable elastic silicone material is performed in the tray.
While producing the pre-impression, it is desirable that the impression material is stable, and thus the insertion of the impression tray filled with putty into the patient's mouth meets resistance. The insertion of the tray is slowed by the resistance, whereby depressing the tray up to the dental surface can be avoided. Contact of the bottom of the tray and the dental surfaces is painful for the patient and leads to an incorrect shape, because there is no longer any impression material present on the contact surfaces.
After removal of the impression from the mouth, the mold is trimmed for removing undercuts and for creating outflow possibilities for the thin flowing silicone material during the second impression (correction impression). The pre-impression is corrected with the second impression in order to increase the detail resolution of the first mold in the cervical and subgingival region. For this purpose, the tooth arch of the first mold is filled in the tray with a low viscosity material of the same chemical nature. If necessary, the prepared tooth is additionally overmolded. By reinserting the tray, the correction material is displaced up to a thin correction layer. It binds with the polymerized first material, and cures as well. During the penetration of the tooth/tooth stump into the hollow space of the first impression filled with the low viscosity material, sufficient pressure is generated to guarantee that the material is also pressed into regions that are difficult to reach, such that even the smallest details of the preparation are precisely reproduced.
The correction impression described above is also called a two-step two-phase impression, because the method is performed successively using two materials of different viscosities with the same chemical basis.
In addition, dental putty masses based on addition curing silicone are also frequently used in a so-called double mix impression. For this purpose, the prepared tooth in the mouth of the patient is overmolded using a low viscosity impression material. While the material is still flowable, the tray with the putty is now placed in the mouth. Both material phases then harden together into a mold.
The double mix impression is also called a one-step two-phase impression, because with this method the tray is filled with the putty and at the same time, the tooth/tooth stump is overmolded with the low viscosity silicone.